The objective of the proposed research is formulation of effective synthetic surfactant to be used in treatment of infant Respiratory Distress Syndrome (RDS). RDS is caused by inadequate levels of lung surfactant at birth, and is presently treated by assisting the newborn with mechanical respiration, a therapy available only at a limited number of medical centers, and one which can severely damage the lungs. Treatment of RDS using natural lung surfactant supplemets appears effective, but is strictly limited by the scarcity of human surfactant proteins, which in addition to phospholipids, are key components of surfactant. The application of recombinant DNA techniques to isolate and express the genes for the human surfactant proteins should provide unlimited quantities of synthetic surfactant formulated with recombinant proteins and pure phospholipids. One of the two major surfactant proteins (SP28-36) has already been cloned and expressed by recombinant DNA methods. We here propose to isolate and express the gene for the remaining human surfactant protein, SP17.